# print(len(set(input().replace('\n',''))))
def count_character(str):
    string = ''.join(set(str))  # 去重后以字符串的形式
    count = 0                   # 开始计数
    for item in string:
        if 0 <= ord(item) <= 127: # ASCII码范围要求
            count += 1         # 计数
    return count
 
str = input()
print(count_character(str))